export default {
  namespaced: true,
  
  state: () => ({
     // 购物车的数组，用来存储购物车中每个商品的信息对象
     // 每个商品的信息对象，都包含如下 6 个属性：
     // { goods_id, goods_name, goods_price, goods_count, goods_small_logo, goods_state }
    cart: JSON.parse(uni.getStorageSync('cart') || '[]')
  }),
  
  mutations: {
    addToCart(state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
          
      if(!findResult) {
        state.cart.push(goods)
      }else {
        findResult.goods_count++
      }   
      this.commit('m_cart/saveToStorage')
    },
    
    saveToStorage(state) {
      uni.setStorageSync('cart', JSON.stringify(state.cart))
    },
    
    //更新购物车的商品勾选状态
    updataGoodsState(state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      
      if(findResult) {
        findResult.goods_state = goods.goods_state
        
        this.commit('m_cart/saveToStorage')
      }
    },
    
    //更新商品数量
    updateGoodsCount(state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      
      if(findResult) {
        findResult.goods_count = goods.goods_count
        
        this.commit('m_cart/saveToStorage')
      }
    },
    
    //根据id删除对应商品
    removeGoodsById(state, goods_id) {
      state.cart = state.cart.filter(x => x.goods_id !== goods_id)
      
      this.commit('m_cart/saveToStorage')
    },
    
    //更新购物车所有商品的勾选状态
    updateAllGoodsState(state, newState) {
      state.cart.forEach(x => x.goods_state = newState)
      
      this.commit('m_cart/saveToStorage')
    }
    
  },
  
  getters: {
    //购物车中所有商品总数
    total(state) {
      // let c = 0
      // state.cart.forEach(x => c += x.goods_count)
      // return c
      
      return state.cart.reduce((total, item) => total+= item.goods_count, 0)
    },
    
    ////购物车中已勾选商品总数
    checkedCount(state) {
      //filter将已勾选的商品过滤出来，reduce将已勾选商品累加
      return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count, 0)
    },
    
    //勾选商品的总价
    checkedGoodsAmount(state) {
      return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count * item.goods_price, 0).toFixed(2)
    }
  }
}